F. BACA
Maize Research Institute Zemun Polje, 11080 Belgrade-Zemun, Yugoslavia
H. BERGER
BFL - Inst. F. Phytomedicine A-1126 Wien, Austria
P. ANGLADE
INRA Station de Zoologie, 33883 Bordeaux, France
and IWGO co-operators*

The fundamental intention of establishing the IWO programme in 1968 was to standardise methodology on resistance testing of maize inbred lines to both, European (ECB - Ostrinia nubilalis Hbn.) and Asian Corn Borers (ACB - Ostrinia furnacalis). In order to achieve set goals, the work of maize breeders and entomologists was united and performed through several stages.
The 14-year results obtained in 14 countries of Europe, Asia and North America are discussed in this paper. As the testing stage is finished, data are unified and some questions important for maize selection can be answered.
Resistance tests were performed by plant artificial infestation with ECB/ACB egg masses. In some countries, wild population egg masses were used, while in others, egg masses of populations; artificially fed were used. Depending on a country, resistance estimations encompassed leaf feeding scores, general damage rating, grain yield, yield response and data on stalk dissection. Inbreds, selected as checks, were evaluated under different agroecological conditions over years. According to results of resistant and susceptible standards, complexity of ECB/ACB dependence on agroecological conditions and inbred responses to larvae causing damage to them are the best observable.
The overall estimation can be determined on the basis of resistance parameters and their correspondence to yield response to damages caused by ECB larvae obtained in Zemun Po1je. Significant differences were observed in all registered resistance parameters over investigation years. Inbred responses to larval damages and pest responses to agroecological conditions were also determined. Results obtained in different countries varied not only over years, but also over inbreds, signifying that the final inbred estimation should been done with caution.
Data on over 360 inbreds were catalogued according to their breeding value and shall be presented in the IWGO Newsletters.
Key words: European corn borer (ECB - Ostrinia nubilalis Asian corn borer (ACB Ostrinia furnacalis)., inbred lines, resistance, productivity.

* W. Faber⁺ (Austria), T. Georgiev and L.Gerginov (Bulgaria), M. Hudon and M.S. Chiang (Canada), D. Zhou (China), P. Anglade (France), B. Dolinka and B. Nagy (Hungary), G. Mariani and F. Coppolino (Italy), C. Kania (Poland), P. Silas (Portugal), D. Mustea (Romania), A. Monteagu⁺ (Spain), D.I. Shapiro⁺, D.S.
Pereverzev and A.N. Frolov (Russia), V. Masler⁺, A. Piovarci⁺, M. Negticki, J. Longauerova and B. Rygava (Slovakia), H.C. Chiang, W.D. Guthria and L.C. Lewis (USA), D. Hadiistevid and Z. Kaitovid, Yugoslavia